When warnings are treated as errors in GDScript, they are appended to
the error list via `push_error()` without regard for line ordering.
This causes them to appear after all other errors in the editor panel,
regardless of their actual line numbers.
Sort errors by line number (with column as tiebreaker) in
`_validate_script()` before display. This ensures the error panel and
the first-error indicator both reflect the correct source order. The
fix is language-agnostic, benefiting all script languages.
Infiland
07d360fbf6